What is sound and how is it produced?

AcademicPhysicsNCERTClass 9


A sound is a form of energy produced by vibrating bodies. Sound is produced when something vibrates. The vibrating body causes the medium (water, air, etc.) around it to vibrate. Vibrations in the air are called traveling longitudinal waves, which we can hear.

How a sound is heard:

We can define a sound wave as a disturbance that travels through some medium. Sound is the term to describe what is heard when sound waves pass through a medium to the ear. All sounds are made by vibrations of molecules through which the sound travels. These vibrations make air molecules move.

Sound needs a medium to travel

Sound needs a medium $(solid,\ liquid,\ gas)$ to travel from one place to another, that's why there is no sound in the vacuum of space as there is nothing to vibrate the sound. Sound travels as waves in the form of compressions and rarefactions$(move\ back\ and\ forth\ quickly)$ which means it vibrates.

Speed of the sound in the air:

At 20 °C, the speed of sound in air is about $343 m/s$.

Updated on 10-Oct-2022 13:23:09